Hand lift truck



Sept. 11, 1956 R. H. GARDNER 2,762,444

HAND LIFT TRUCK Filed NOV. 25, 1953 2 Sheets-Sheet 1 FIG. I

INVENTOR. RICHARD H. GARDNER VOW 6km ATTY.

Sept. 11, 1956 Filed Nov. 25, 1953 R. H. GARDNER HAND LIFT TRUCK 2Sheets-Sheet 2 RICHARD H. GARDNER 0 EM m ATT Y.

United States Patent-O HAND LIFT TRUCK Richard H. Gardner,Buchanan,,Mich., assignor to Clark Equipment Company, a corporation ofMichigan Application November 25, 1953, Serial No. 394,411 Claims. 01.180-13) My present invention relates generally to power operated handlift trucks, and, more specifically, to drive head mounting meanstherefor.

Presently known powered hand lift trucks commonly are comprised of theprimary elements of a main frame and a drive head rotatably mountedtherein about a vertical axis. The drive head is supported on the drivewheel of the truck and generally carries the prime mover means forpowering the truck. A handle is attached to the drive head and isadapted to be manually swung in a horizontal plane for pivoting thedrive head and steering the vehicle.

As will be realized by those skilled in the art, the direction of driveof a hand lift truck is continually changed while the truck is beingpositioned to engage or deposit a load. Consequently it is importantthat the mounting between the truck frame and drive unit be of suchconstruction that a minimum of eifort is required to pivot the steeringhead. Also it is important to eliminate chatter between the drive unitand the frame such as sometimes occurs with conventional constructions.

It is an object of my present invention to provide means for mounting adrive head in a truck frame which means will permit limitary fore andaft floating movement of the drive unit relative to the frame so as toprovide free turning of the drive head and substantially eliminatechatter of the head during changes in direction of drive of the truck.

A further object of my invention is the provision of a constructionformountinga drive head in a truck frame which is low in cost and whichallows moderate manufacturing eccentricities and tolerances withoutadverse effect on its operation.

In accomplishing the above objects, I form the main frame with aninternal track having the wall thereof extending vertically.Circumferentially spaced rollers; are mounted about vertical axes inresilient means carried by the drive head and the rollers are disposedin engagement with the track of the main frame for rotatably mountingthe drive head in the latter. The resilient floating mounting of therollers serves to eliminate chatter of .the

drive unit during changes in direction of drive of the truck.

It is a further feature of my present invention that the resilientmeans, in which the rollers are mounted, are pre-stressed duringassembly of the machine, thereby improving the elimination ofundesirable chatter. Pre -stressing is obtained by forming the diameterof the track smaller than the diameter of a circle which is tangent tothe outer peripheries of the rollers when the drive head unit isdemounted from the main frame. As a result, the rollers, when assembledin engagement with the track, are positioned radially inwardly of theirnormal free positions, and the desired stress in the resilient mountingsis thereby created.

Now, in order to acquaint those skilled in the art with the manner ofconstructing and using drive head mounting means in accordance with theprinciples of my present invention, I shall describe in connection withthe accom- 'ice .section of a hand lift truck with which my presentinvention is embodied; and

Figure 2 is a partial plan view of the hand lift truck of Figure 1 withthe cover and other parts above the drive head removed. 4 1

' Referring now to the drawings, there is indicated generally by thereference numeral 10 a hand lift truck which comprises a main frame 12and load supporting means 14 projecting forwardly therefrom. The loadsupporting means 14 in the specific embodiment shown includes a pair ofhorizontal fork frames vertically movable relative to the body portion12 through the actuation of a pair of hydraulic piston and cylinderassemblies 16 (acting through conventional linkages which are not shownin the drawing) arranged respectively adjacent the sides of the truck10. The load supporting forks 14 at their forward ends are supported onextensible groundengaging rollers in a manner which is well known in theart.

Rotatably mounted, about a vertical axis, in the main frame 12 is adrive head unit, indicated generally by the reference numeral 18, whichis supported on a ground engaging drive wheel 20. The drive wheel 20ispowered by an electric motor 49 which is enclosed in the drive headunit 18. The electric motor is adapted to have driving connection withthe drive wheel 20 through suitable gearing, and is adapted to haveelectrical connection with a battery (not shown) carried by the truck 10through a-pair of clock-like springs 21 which are arranged at the upperend of the drive head unit 18. The battery may be located in the space51 and electrical connections made from the battery terminals to springs21 respectively. Since the drive means of the hand lift truck forms nopart of my present invention, it is believed that the foregoingdescription thereof is sufficient for purposes of the presentdisclosure.

. Thehand lift truck 10 may include a motor driven pump 53 havingsuitable electrical and hydraulic connections (not shown) for operatinghydraulic devices on the truck such as piston and cylinder assemblies16.

The upper end of the drivehead unit 18 is secured in the inner race ofa-tapered roller bearing assembly 22 which preferably is of the selfaligning type and which is arranged immediately below the electricalconducting springs 21. The outer race of the assembly 22 is secured in ahorizontal plate member 23 suitably bolted to the main frame 12. Themeans of my present invention for guiding andv restricting fore and aftmovement of the drive head unit 18 in the main frame 12 comprises ahorizontal circular ring member 24 which is non-rotatably secured to themain frame 12 by means of a plurality of circumferentially spaced bolts26. The internal diameter or vertical wall of the ring 24 defines atrack 28 which is engageable by a plurality of circumferentially spacedrollers 30. The rollers 30 number four in the specific embodiment of theinvntion disclosed herein and are mounted on vertical needle bearings 32which surround vertical supporting shafts 34. The upper and lower endsof the shafts 34 have resilient ring members 36 disposed thereaboutwhich are fixed in vertically spaced bracket members 38 extendingradially and horizontally from the drive head unit 18. The shafts 34 aremaintained in proper position by means of conventional washers andretainer rings.

The resilient mounting of the shafts 34 permits lim-itary fore and aftfloating movement of the drive head unit 18 relative to the main frame12 of the truck 10 so as to thereby reduce chatter of the drive headunit 18 during changes in direction of drive of the truck. In order tofurther reduce and substantially eliminate chatter, the re ville supportfor a horizontal pin member-42, V I ti -ember 42 has secured thereon thelower end of a normam frame 12. 'I'hen, the rollers 30 as they arepositioned into engagement with the track, are moved radially inwardlyof their normal free positions, and the desired stress the resilientmountings is thereby attained. The drive head unit 18 is also formedwith a pair of horizontally spaced vertical flange members 40 which pro-The pin m t-1y apwaraiy extending steering handle 44 which has a kennelhead 46 at its upper end with hand grips 48 "exterl dirtg laterallytherefrom. The details of construcand operation of thecontrol head 46will not be denbe'd herein since it forms no part of my presentinvention; The handle ma be swung in a vertical plane from the positionshown in Figure 1 to a substantially horizontal position, although,normally, means are provided for bias ihg the handle 44 toward avertical position. The handle 44 may be grasped at the hand grips 48 andswung in a horizontal plane for effecting rotary movement of thedriveunit 18 within the main frame 12 for steering the vehicle.

From the foregoing description, it win he realized by those skilled inthe art that I have provided drive head -'rnoun'tirig-means which iseffective in reducing the transrnission of shoks between the drive headunit and the complementary portions of a hand lift truck. Thus, wear 'ofthe truck is reduced and the truck becomes easier and means, such asballs, suitably mounted in resilient means an be employed if desired.

Thus, while I have shown and described what I believe to be a preferredembodiment of my present invention, it

he understoodthat various rearrangements and modiaestieas may be madetherein without departing from the spirit and scope of my invention 1claim: K LfIn a hand lift truck having a mainframe and a drive head unitincludingia ground engaging drive wheel, means forinoti'riting the drivehead unit in'the main frame for rotation about a vertical axis, and saidmounting means including anti-friction means mounted in resilient meanswhich permits liniitary fore and aft floating movement of the drive headunit relative to the main frame so as to reduce chatter of the unitduring changes in direction of drive of the truck. I

2. In a hand lift truck having a main frame and a drive headunitineluding a ground engaging drive wheel, a pluextending vertically,eircumfere'ntially spaced rollers rotatably mounted in the drive headunit about vertical axes, saidrollers engaging thetrack of the mainframe whereby the unit is mounted in the main frame for rotation about avertical axis, and said rollers being fioatingly biased radiallyoutwardly so as to reduce chatter of the unit during changes indirection of drive of the truck.

4. In a hand lift truck having a main frame and a drive head unitincludinga ground engaging drive wheel, said main fraine having aninternal track with the wall thereof extending vertically,circumferentially spaced rollers mounted about vertical axes inresilient means carried by said drive head-unit, Said rollers engagingthe track of the main frame whereby "said unit is mounted in said mainframe for rotation about a vertical axis, and the resilient mounting ofsaid rollers serving to permit limitary fore and aft floating movementof said unit relative to said main frame so as to reduce chatter of saidunit during changes in direction of drive of the truck.

5; In a hand lift truck having a main frame and a drive head unitincluding a ground engaging drive wheel, circumferentially spacedrollers mounted about vertical tries in resilient means carried by saiddrive head unit,

'about'a vertical axis; said rollers when assembled in engagement withsaid track being positioned radially inwardly of their normalfreepositions for stressing the resilient mountings, and the stressedresilient mountings of said rollers serving to permit limitary fore andaft floating indv'e'ment' of said unit relative to said main frame so asto reduce chatter (if said unit during changes in direction of the driveof the truck.

References Cited in the tile of this patent UNITED STATES PATENTS862,267 Meyer Aug. 6, i907 FOREIGN PATENTS 272,838 Italy Mar. 22, 1930635,646 Great Britain Apr. 12, 1950 "1,015,557 France Oct. 15, 1952

